Overcharging Problem

Hello folks,

I have been having a few problems with my electric system lately and I am still a little non-the wiser. My alternator appeared to be overcharging my battery. I had a reading of 15V across the battery terminals, so I ordered a new regulator from eBay and installed it, only to find that I now get a reading of 16.8V+ across the battery terminals I have also found that if I rev the engine, the voltage across the battery reduces to 16V. If I let the engine idle, the voltage slowly creeps back up.

What the hell is going on here!?
Is it likely to be my battery that is at fault or still a problem with the alternator?

Thanks,
-Tom

disconnect battery antd check it ,but likely alternator

jamesmartin said:

disconnect battery antd check it ,but likely alternator

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Will do. Can't it do more harm than good running the engine without a battery connected? Such as burning out the regulator? I was under the impression that a regulator prevented the alternator from overcharging full-stop.

-Tom

You wont get proper readings by disconnecting the battery. The regulator needs a reference voltage to operate correctly and as you say may burn out.
I'd beg steal or borrow another battery and see if it makes any difference. That way you'll know if your battery is on its way out.

i didnt mean run engine with battery off just disconnect lead and test battery voltage will be 12v but its a good thing to rule out everything funny things some times do happen ,

Thanks for the replies. Well I have done a little more investigating today and it has brought back some different results. I have tested the voltage reading across the battery terminals with three different multimetres, two of which I believe must have flat batteries which have provided false readings. I am now getting a reading of 13V from the battery with the engine off, which increases to 14.6V whilst the engine is running. The voltage then fluctuates slightly between 14.4 and 14.6V with the engine held at a higher rpm. I think it is safe to say that my alternator is not currently overcharging my battery BUT there is however, still a horrible sulphury / acidy smell coming from the battery. I checked and topped up the levels in all six cells and cleaned the terminals. What would be causing the foul smell? Is it just my battery getting a bit past it's best or am I still missing something?

Thanks,
-Tom

If it needed topping up and smelling its probably on its last knockings.
14.4/6 is perfect and is what mine is chucking out.


Lynall

If the battery is gassing like that and the alternator output is now OK then the battery is shot. Get a new one before it dies. Apart from anything else, on a Defender the fumes are likely to end up in the cab with you. Not pleasant.